The semiconductor integrated circuit (IC) industry has experienced rapid growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. However, these advances have increased the complexity of processing and manufacturing ICs and, for these advances to be realized, similar developments in IC processing and manufacturing are needed. In the course of integrated circuit evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component (or line) that can be created using a fabrication process) has decreased.
As a part of the semiconductor fabrication, conductive elements may be formed to provide electrical interconnections for the various components for an IC. For example, conductive vias for interconnecting different metal layers may be formed by etching openings in an interlayer dielectric (ILD) and filling the openings with a conductive material. However, as semiconductor fabrication technology nodes continue to evolve, critical dimensions and pitches are becoming smaller and smaller, and the process windows are becoming tighter. Consequently, overlay errors (e.g., misaligned via) may occur, which may lead to problems such as reduced reliability test margin or poor device performance.
Therefore, while conventional via formation processes have been generally adequate for their intended purposes, they have not been entirely satisfactory in every aspect.